Synthesis and Experimental Study of New Coumarin Derivatives as a Corrosion Inhibitor for Carbon Steel Surface in 1 M HCl

One common method of protecting carbon steel against corrosion is the use of organic compounds. The goals of the research are to assess the corrosion resistance of coumarin sulfonamides containing imine and phosphine imine. 4, 7-dimethyl coumarin was reacted with chloro sulfonic acid to produce 4,7-dimethyl-6-chlorosulphonyl coumarin [B], which was then reacted with hydrazine hydrate [C] to obtain the corresponding sulfonyl hydrazide. Finally, Schiff base derivatives were created by treating the coumarin with various aromatic aldehydes. Also, Sulfonyl azide coumarin derivative was produced by reacting [B] with sodium azide then Sulfonyl azide coumarin derivative reacts with triphenyl phosphine P(Ph)3 to form corresponding phosphinimine coumarin. Chemical and physical characterization tests were used to investigate and determine the most corrosion-resistant compound among all the produced compounds. Structures of the synthesized compounds were elucidated on the basis of Rƒ, FTIR, 1H-NMR, and 13C-NMR spectroscopy, which agreed with the proposed structures. All synthesized compounds were found to have exhibited corrosion resistance in HCl solutions in different temperatures (293, 303, and 313 K). AFM demonstrated that [M6] compounds decreased carbon steel surface roughness to 59.28 nm. The FESEM indicated that the blank sample’s surface was extensively corroded, excessively rough, [M6] smoothed, and reduced the damage. The EDS shows that [M6] is adsorbed on carbon steel since it contains Fe, C, O, N, and S. Physisorption deposited [M6] on the surface, according to XRD.The [M6] compound in HCl solution is the best corrosion resistance in different temperature (293, 303, and 313 K).